JP3452123B2 - Method for manufacturing SOI substrate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SO in which a semiconductor layer is provided on an insulating film manufactured by using a hydrogen ion implantation technique.
The present invention relates to a method for manufacturing an I (Silicon On Insulator) substrate.

[0002]

2. Description of the Related Art This type of SOI substrate has been drawing attention as a future ultra high integrated circuit (ULSI) substrate. This S
The method of manufacturing an OI substrate includes a method of bonding silicon substrates to each other via an insulating film, a method of depositing a silicon thin film on an insulating substrate or a substrate having an insulating thin film on its surface, and a high concentration inside a silicon substrate. After the implantation of oxygen ions, an annealing process is performed at a high temperature to form a buried silicon oxide layer in a region of a predetermined depth from the surface of the silicon substrate, and a SIMOX method using the Si layer on the surface side as an active region is available. . Also, recently, after implanting hydrogen ions or the like into a semiconductor substrate, this semiconductor substrate is stacked on a support substrate with the ion implantation surface as a stacking surface, and this stack is formed into a stack of 500
There has been proposed a method for producing a thin semiconductor material film having a semiconductor thin film on the surface of the supporting substrate by separating the semiconductor substrate from the supporting substrate in a region in which the hydrogen ions are implanted by raising the temperature to a temperature in excess of ° C. (JP-A-5-21112
8). In this method, if ions can be uniformly injected into the semiconductor substrate from the surface, a semiconductor substrate having a thin semiconductor layer with a uniform thickness can be obtained. Further, if an oxide film is provided on the surface of the supporting substrate in advance, the supporting substrate, the oxide film formed on this substrate and acting as a buried oxide film, and the semiconductor layer formed on this oxide film are provided by this method. SO
An I substrate can be manufactured.

[0003]

However, when the semiconductor layer formed on the oxide film is contaminated by heavy metal impurities during the device process, the buried oxide film forms a gettering layer having a gettering ability. After the heavy metal impurities have been captured, the oxide layer crystallized with the progress of the heat treatment releases the heavy metal impurities once captured into the semiconductor layer and easily re-distributes, which causes contamination of the semiconductor layer. There is a problem that quality deterioration occurs due to. An object of the present invention is to provide an SO in which a semiconductor layer manufactured by using a hydrogen ion implantation technique is overlaid on a semiconductor substrate with an oxide film interposed therebetween.
An object of the present invention is to provide a method for manufacturing an SOI substrate having a large gettering ability and preventing the semiconductor layer from being contaminated with heavy metal impurities in the I substrate.

[0004]

The invention according to claim 1 is
As shown in FIG. 1, a step of forming an oxide film 12 on the surface of the p-type first silicon substrate 11 and the first silicon substrate 11
By implanting hydrogen ions from the surface of the first silicon substrate 11
The step of forming the hydrogen ion implantation region 11a therein and p ^{+ on} one surface of the p-type second silicon substrate 13 serving as a supporting substrate
A p-type or p ⁺⁺ -type polysilicon layer 14;
A step of forming a p ⁻ -type polysilicon layer 16 on the p ⁺ -type or p ⁺⁺ -type polysilicon layer 14 of the second silicon substrate 13, and a step of mirror-polishing the p ⁻ -type polysilicon layer 16. , A step of superposing and adhering the second silicon substrate 13 on the first silicon substrate 11 so that the p ⁻ -type polysilicon layer 16 adheres to the oxide film 12, and the first silicon substrate 11 on the second silicon substrate 13. The first silicon substrate 11 is separated from the second silicon substrate 13 in the hydrogen ion implantation region 11a by heat treatment at a predetermined temperature while being in contact with the second silicon substrate 11.
This is a method for manufacturing an SOI substrate including a step of forming a silicon layer 11b on the surface of the silicon substrate 13 and a step of further heat-treating the second silicon substrate 13 having the silicon layer 11b on the surface. As shown in FIG. 1, since the p ⁻ type polysilicon layer 16 and the p ⁺ type or p ⁺⁺ type polysilicon layer 14 are formed on the lower side of the oxide film 12 so as to be in close contact therewith, the silicon Even if the layer 11b is contaminated by heavy metal impurities during the device process, the p ⁻ -type polysilicon layer 16
And the p ⁺ type or p ⁺⁺ type polysilicon layer 14 acts as a gettering layer. This is because the silicon grain boundaries in the polysilicon layer getter the heavy metal impurities. Further, defects are likely to occur in the p ⁺ type or p ⁺⁺ type polysilicon layer. This defect increases the gettering ability. Further, since boron forms a stable iron-boron pair with heavy metal impurities such as iron, a p ⁺ type or p ⁺⁺ type polysilicon layer having a high boron concentration also has a gettering ability for heavy metal impurities. high.
That is, the heavy metal impurities in the silicon layer 11b are removed by the oxide film 12.
Through the p ⁻ -type polysilicon layer 16 and the p ⁺ -type or p-type
^The silicon layer 11b is trapped by the ^{+ +} type polysilicon layer 14 and is not contaminated with heavy metal impurities even if heat treatment proceeds.
Further, the oxide film 12 and the p ⁺ type or p ⁺⁺ type polysilicon layer 1
Since the p ⁻ type polysilicon layer 16 is formed between the silicon layer 1 and the semiconductor layer 4, the thickness of the p ⁻ type polysilicon layer 16 is changed according to the device design.
It is possible to suppress the influence on the spread of the depletion layer during the operation of the element formed in 1b.

[0005]

[0006] The invention according to claim 2, as shown in FIG. 2, injection forming an oxide film 12 on the surface of the first silicon substrate 11 of p-type, the hydrogen ions from the surface of the first silicon substrate 11 Then, the step of forming the hydrogen ion implantation region 11a inside the first silicon substrate 11 and the step of forming a support substrate p
A step of ion-implanting phosphorus from the surface of the second silicon substrate 13 of the mold to form a phosphorus injection layer 13a inside the second silicon substrate 13, and p ^{− on} the surface of the second silicon substrate 13 on which the phosphorus injection layer 13a is formed. Forming a p ^- type polysilicon layer 16, mirror-polishing the p ⁻ -type polysilicon layer 16, and the first step so that the mirror-polished p ⁻ -type polysilicon layer 16 adheres to the oxide film 12. Silicon substrate 1
1 and the step of bringing the second silicon substrate 13 into close contact with each other, and the first silicon substrate 11 is heat-treated at a predetermined temperature while being brought into close contact with the second silicon substrate 13 so that the first silicon substrate 11 is subjected to the hydrogen ion implantation region 11a. And a step of separating the second silicon substrate 13 from the second silicon substrate 13 to form a silicon layer 11b on the surface of the second silicon substrate 13, and the silicon layer 11b on the surface.
And a step of further heat-treating the second silicon substrate 13 having the above. As shown in FIG. 2 , since the phosphorus implantation layer 13a is formed inside the second silicon substrate 13 below the oxide film 12, even if the silicon layer 11b is contaminated by heavy metal impurities during the device process, The P ⁻ type polysilicon layer 16 and the phosphorus implantation layer 13a act as a gettering layer. That is, the heavy metal impurities in the silicon layer 11b pass through the oxide film 12 and are captured by the phosphorus implantation layer 13a, so that the silicon layer 11b is not contaminated with the heavy metal impurities even if the heat treatment proceeds. Also oxide film 1
Since the p ⁻ type polysilicon layer 16 is formed between the 2 and the phosphorus implantation layer 13a, the silicon layer is changed by changing the thickness of the p ⁻ type polysilicon layer 16 according to the device design. It is possible to suppress the influence on the spread of the depletion layer during the operation of the element formed in 11b.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, in order to manufacture the SOI substrate of the first embodiment of the present invention, first, a p-type first
A single crystal silicon substrate 11 is prepared. The first single crystal substrate 11 is manufactured by using boron (B) as a dopant. An oxide film 12 which is an insulating layer is formed on the surface of the first single crystal substrate 11 by thermal oxidation (FIG. 1).
(A)). The oxide film 12 is formed to have a thickness of 0.1 to 2 μm, preferably 0.1 to 0.5 μm.
Next, hydrogen ions are ion-implanted from the surface of the p-type single crystal substrate 11 having the oxide film 12 at a dose amount of 1 to 10 × 10 ¹⁶ / cm ² and an acceleration energy of 50 to 200 keV. As a result, the ion-implanted region 11a is formed inside the single crystal substrate 11 (FIG. 1B). Next, a p-type second single crystal silicon substrate 13 having the same surface area as that of the single crystal substrate 11 and serving as a supporting substrate is prepared, and a p ⁺ type or p ⁺ type is formed on the surface of the second single crystal substrate 13 by the CVD method. ^{A +} type polysilicon layer 14 is formed (FIG. 1C). The p ⁺ type or p ⁺⁺ type polysilicon layer 14 is the p type first single crystal substrate 1
It is formed by increasing the concentration of boron, which is a dopant, more than 1. The polysilicon layer 14 is formed to have a thickness of 0.5 to 3 μm, preferably 0.5 to 2 μm. Then, this p ⁺ type or p ⁺⁺ type polysilicon layer 14 is formed.
A p ⁻ type polysilicon layer 16 is formed thereon (FIG. 1).
(D)). The p ⁻ type polysilicon layer 16 is 0.5 to
It is formed to have a thickness of 3 μm, preferably 0.5 to 2 μm. The p ⁻ type polysilicon layer 16 is formed with a boron concentration lower than that of the p ⁺ type or p ⁺⁺ type polysilicon layer 14. Preferably, it is equivalent to the first single crystal substrate 11. Next, the p ⁻ type polysilicon layer 16 is mirror-polished to be planarized. Next, after cleaning the first single crystal substrate 11 and the second single crystal substrate 13, respectively, the first single crystal substrate 1 is so arranged that the p ⁻ type polysilicon layer 16 is adhered to the oxide film 12.
The second single crystal substrate 13 is overlaid on and closely adhered to the substrate 1 (FIG. 1E). Next, while keeping the first single crystal substrate 11 in close contact with the second single crystal substrate 13, 500 to 800 in a nitrogen atmosphere.
The temperature is raised to the range of ° C and held for 5 to 30 minutes to perform the thin film separation heat treatment. As a result, the first single crystal substrate 11 is cracked at the ion implantation region 11a corresponding to the hydrogen ion implantation peak position, and the thick portion 11c in the upper portion and the thin semiconductor layer 1 in the lower portion are cracked.
It is separated into 1b (FIG. 1 (f)). Next, the temperature is lowered to remove the thick portion 11c (FIG. 1 (g)). Then, the second single crystal substrate 13 on which the p ⁺ type or p ⁺⁺ type polysilicon layer 14, the p ⁻ type polysilicon layer 16, the oxide film 12 and the semiconductor layer 11b are sequentially stacked on the surface is placed in an oxygen or nitrogen atmosphere. At 900 to 1200 ° C. for 30 to 120 minutes,
The semiconductor layer 11b and the second single crystal substrate 13 are p ⁺ -type or p-type.
⁺⁺ type polysilicon layer 14, p ⁻ type polysilicon layer 1
6 and the oxide film 12 are firmly bonded to each other (see FIG. 1).
(H)). Finally, the separation surface of the semiconductor layer 11b and the thick portion 1
The separation surfaces of 1c are each smoothed by polishing (touch polishing) (FIG. 1 (i) and FIG. 1 (j)). As a result, the second single crystal substrate 13 becomes an SOI substrate, and the thick portion 11
c can be reused as a new semiconductor substrate for manufacturing the SOI substrate.

[0008]

[0009] FigureTwoAs shown in FIG.TwoImplementation form of
First Embodiment Based on FIG.
Repeating the same steps as in the above, the p-type first single crystal silicon
An oxide film 12 is formed on the surface of the substrate 11 (see FIG.Two
(A)). Then, as in the case of the first embodiment, the oxide film 12 is formed.
Hydrogen ions are implanted from the surface of the first single crystal substrate 11 having
To form the ion-implanted region 11a inside the substrate 11.
(FigureTwo(B)). Then, the first single crystal silicon substrate 11 and
A p-type second single crystal substrate having the same surface area and serving as a supporting substrate.
A recon substrate 13 is prepared, and the p-type second single crystal substrate 1 is prepared.
The second single crystal substrate 13 by ion-implanting phosphorus from the surface of
A phosphorus injection layer 13a is formed inside (see FIG.Two(C)). Next
Of the second single crystal substrate 13 on which the phosphorus injection layer 13a is formed.
P on the surface^-Forming a polysilicon layer 16 of the mold (Fig.Two
(D)). This p^-The polysilicon layer 16 of the mold is 0.5 to
To a thickness of 3 μm, preferably 0.5-2 μm
Form. p^-The boron concentration of the polysilicon layer 16 of the mold is
It is preferably the same as the first single crystal substrate 11. Next
And p^-The polysilicon layer 16 of the mold is mirror-polished and flattened.
It Next, the first single crystal substrate 11 and the second single crystal substrate 13 are
After cleaning each, p is applied to the oxide film 12.^-Type of polysilico
A second single crystal substrate 11 so that the first single crystal substrate 11 is in close contact with the second single crystal substrate 11.
The crystal substrates 13 are overlapped and brought into close contact with each other (Fig.Two
(E)). Then, the first single crystal substrate 11 is replaced with the second single crystal substrate.
The same thin film separation heat treatment as that of the first embodiment while keeping it in close contact with 13.
I do. As a result, the first single crystal substrate 11 is ion-implanted.
The thick part 11c at the top and the thick part 11c at the bottom
Separate into thin semiconductor layers 11b (Fig.Two(F)). Next warm
Lower the thickness to remove the thick part 11c (Fig.Two(G)), surface
To p^--Type polysilicon layer 16, oxide film 12 and semiconductor layer
The second single crystal substrate 13 in which 11b are sequentially laminated is used as the first embodiment.
In the same manner as in the above case, the semiconductor layer 11b and the second single crystal are heat-treated.
Substrate 13 and oxide film 12 and p^-Type polysilicon layer 16
Stick firmly via (Fig.Two(H)). Finally half
Separate the separation surface of the conductor layer 11b and the separation surface of the thick portion 11c.
Polish and smooth each (Fig.Two(I) and figureTwo
(J)). This allows p on the surface^-Type polysilicon layer 1
6, an oxide film 12 and a semiconductor layer 11b are sequentially stacked.
2 Obtain an SOI substrate composed of a single crystal substrate 13 (see FIG.Two
(I)).

[0010]

EXAMPLES Next, examples of the present invention will be described together with comparative examples in order to show specific embodiments of the present invention. <Example 1> As shown in FIG. 1A, an oxide film 12 having a thickness of 400 nm was formed on the surface of a p-type single crystal silicon substrate 11 by thermal oxidation. Then, a voltage of 70 keV is applied to the single crystal silicon substrate 11 to generate hydrogen ions at 7 × 10 ¹⁶ /
Ions were implanted with a dose of cm ² to form an ion-implanted region 11a inside the single crystal substrate 11 (FIG. 1B). Next, a p-type second single-crystal silicon substrate 13 serving as a supporting substrate having the same surface area as the single-crystal substrate 11 is prepared, and the surface of the second single-crystal substrate 13 is p ⁺ -type or p-type having a thickness of 1 μm by the CVD method. ^{A ++} type polysilicon layer 14 was formed (FIG. 1C). Then, a p ^- type polysilicon layer 16 having a thickness of 1 μm is formed on the p ⁺ type or p ⁺⁺ type polysilicon layer 14.
Was formed (FIG. 1 (d)). Then, the p ⁻ -type polysilicon layer 16 was mirror-polished and flattened. Then, the first single crystal substrate 11 and the second single crystal substrate 13 are each washed with SC1 cleaning liquid, and then the p ^- type polysilicon layer 1 is formed on the oxide film 12.
The second single crystal substrate 13 was superposed on and adhered to the first single crystal substrate 11 so that 6 adhered to each other (FIG. 1E). Then, heat treatment was performed for 30 minutes at a temperature of 600 ° C. in a nitrogen atmosphere while the first single crystal substrate 11 was in close contact with the second single crystal substrate 13. As a result, the first single crystal substrate 11 was cracked at the ion implantation region 11a and separated into an upper thick portion 11c and a lower thin semiconductor layer 11b (FIG. 1 (f)). Next, the temperature is lowered to remove the thick portion 11c (FIG. 1 (g)), and p ⁺ type or p ⁺⁺ type polysilicon layer 14, p ⁻ type polysilicon layer 16, oxide film 12 and The second single crystal substrate 13 in which the semiconductor layers 11b were sequentially stacked was heat-treated at 1100 ° C. for 2 hours in a nitrogen atmosphere (FIG. 1 (h)). Finally, the separation surface of the semiconductor layer 11b was polished and smoothed to obtain the first embodiment.
The SOI substrate was manufactured (FIG. 1 (i)).

[0011]

[0012] <Example 2> FIGS. 2 (a) as shown in to FIG. 2 (b), repeating the same process as in Example 1, a first p-type having an oxide film 12 having a thickness of 400nm on the surface An ion implantation region 11 a was formed inside the single crystal silicon substrate 11. Next, a p-type second single crystal silicon substrate 13 having the same surface area as the first single crystal silicon substrate 11 and serving as a supporting substrate is prepared.
Phosphorus is ion-implanted from the surface of the single crystal substrate 13 to form a phosphorus implantation layer 13a inside the second single crystal substrate 13 (FIG. 2 ).
(C)). Then the 2 p thick 1μm on the surface of the single crystal substrate 13 formed with phosphorus implantation layer 13a ^- to form a type polysilicon layer 16 (Figure 2 (d)). Next, the p ⁻ -type polysilicon layer 16 was mirror-polished and planarized. Then the first
After cleaning the single crystal substrate 11 and the second single crystal substrate 13 with the SC1 cleaning liquid respectively, the first single crystal substrate 11 and the second single crystal silicon substrate are adhered to the oxide film 12 so that the p ⁻ type polysilicon layer 16 is adhered thereto. 13 were overlapped and brought into close contact (Fig. 2 ).
(E)). Then, heat treatment was performed for 30 minutes at a temperature of 600 ° C. in a nitrogen atmosphere while the first single crystal substrate 11 was in close contact with the second single crystal substrate 13. As a result, the first single crystal substrate 1
1 cracked at the ion-implanted region 11a and separated into an upper thick portion 11c and a lower thin semiconductor layer 11b (FIG. 2 ).
(F)). Next, the temperature is lowered to remove the thick portion 11c (see FIG.
2 (g)), the second single crystal substrate 13 having the p ⁻ -type polysilicon layer 16, the oxide film 12 and the semiconductor layer 11b sequentially stacked on the surface was heat-treated at 1100 ° C. for 2 hours in a nitrogen atmosphere (FIG. 2 ). (H)). Finally, the separation surface of the semiconductor layer 11b was polished and smoothed to manufacture the SOI substrate of Example 2 (FIG. 2 (i)).

Comparative Example 1 A p ⁺ -type or p ⁺⁺ -type polysilicon layer 14 and a p ⁻ -type polysilicon layer 16 are formed on the surface of a p-type second single crystal silicon substrate 13 serving as a supporting substrate. The SOI substrate of Comparative Example 1 was manufactured by substantially repeating the method of Example 1, except that the SOI substrate was not used.

[0014] <Comparative Evaluation> In each of the SOI substrate of Example 1, Example 2及 beauty Comparative Example 1, forcibly contaminate the substrate surface by spin coating using a copper standard solution of 1000 ppm, a nitrogen atmosphere After heat treatment at 900 ° C. for 1 hour in the inside, the copper concentration (atoms / cm ³ ) in the semiconductor layer 11b was examined by an atomic absorption method. The results are shown in Figure 3.

As is clear from FIG . 3 , the copper concentration (atoms / cm ³ ) in the SOI layers of Examples 1 and 2 is lower than that of Comparative Example 1. This indicates that the SOI substrates of Examples 1 and 2 have a large gettering ability, and thus the semiconductor layer 11b is less likely to be contaminated with heavy metal impurities than the SOI substrate of Comparative Example 1.

[0016]

As described above, according to the present invention, in the SOI substrate in which the semiconductor layer is superposed on the semiconductor substrate via the oxide film, one surface of the p-type single crystal silicon substrate to be the semiconductor substrate is formed. to form a p ⁺ -type or p ⁺⁺ type polysilicon layer, p the polysilicon layer ^- either -type polysilicon layer, or the surface of the support substrate on which the phosphorus implanted layer is formed Since the p ⁻ type polysilicon layer is formed, even if the semiconductor layer is contaminated by heavy metal impurities during the device process, the p ⁻ and p ⁺ type or p ⁺⁺ type polysilicon layer or the phosphorus layer is formed. The injection layer acts as a gettering layer to capture the heavy metal impurities in the semiconductor layer, and as a result, the silicon layer is not contaminated with the heavy metal impurities even if the heat treatment proceeds, and the quality deterioration of the SOI substrate can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of manufacturing a first SOI substrate according to an embodiment of the present invention in the order of steps.

FIG. 2 is a diagram showing a method of manufacturing a second SOI substrate according to the embodiment of the present invention in the order of steps.

FIG. 3 is a diagram showing the copper concentration in a semiconductor layer 11b in the SOI substrates of Examples 1 and 2 and Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-212128 (JP, A) JP-A-9-162090 (JP, A) JP-A-9-237884 (JP, A) JP-A-6- 163862 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/265 H01L 21/322 H01L 21/762 H01L 27/12

Claims (2)

(57) [Claims] 1. A step of forming an oxide film (12) on the surface of a p-type first silicon substrate (11), and implanting hydrogen ions from the surface of the first silicon substrate (11) to form the first silicon The step of forming the hydrogen ion implantation region (11a) inside the substrate (11), and the p-type second silicon substrate (13) serving as a supporting substrate are provided with p
Forming a ⁺ type or p ⁺⁺ type polysilicon layer (14), and forming a p ⁻ type polysilicon layer (14) on the p ⁺ type or p ⁺⁺ type polysilicon layer (14) of the second silicon substrate (13). forming a polysilicon layer (16), wherein the p ^- type polysilicon layer (16) wherein p is mirror polished to a step of mirror polishing, the oxide film (12) ^- type polysilicon layer (16) So that the first silicon substrate (11) and the second silicon substrate (13) are overlapped and brought into close contact with each other, and the first silicon substrate (11) is brought into close contact with the second silicon substrate (13). The first silicon substrate (11) is separated from the second silicon substrate (13) in the hydrogen ion implantation region (11a) by heat-treating at a predetermined temperature while keeping the second silicon substrate (13).
Forming a silicon layer (11b) on the surface of the substrate, and the second silicon substrate having the silicon layer (11b) on the surface
A method of manufacturing an SOI substrate, further comprising the step of further heat treating (13) . 2. A step of forming an oxide film (12) on the surface of a p-type first silicon substrate (11), and hydrogen ions being implanted from the surface of the first silicon substrate (11) The step of forming a hydrogen ion implantation region (11a) inside the substrate (11), and the second silicon substrate (13) by ion-implanting phosphorus from the surface of the p-type second silicon substrate (13) serving as a supporting substrate. A step of forming a phosphorus injection layer (13a) therein, and a second silicon substrate (13) having the phosphorus injection layer (13a) formed therein
Type ^- forming type polysilicon layer (16), the p ^{- -} p on the surface of the p type and steps of the polysilicon layer (16) mirror-polishing, which were mirror-polished to said oxide film (12) Of the first silicon substrate (11) so that the polysilicon layer (16) of the first silicon substrate (11) is in close contact with the first silicon substrate (11), and the first silicon substrate (11) is in contact with the second silicon substrate (11). The first silicon substrate (11) is separated from the second silicon substrate (13) in the hydrogen ion implantation region (11a) by heat treatment at a predetermined temperature while being in close contact with the substrate (13), and then the second silicon substrate (11) is separated. Board (13)
Forming a silicon layer (11b) on the surface of the substrate, and the second silicon substrate having the silicon layer (11b) on the surface
A method of manufacturing an SOI substrate, further comprising the step of further heat treating (13).